Spinal fusion is a surgical technique by which two or more vertebrae are joined together. This technique is used to treat various conditions such as, for example, spinal deformities, damaged spinal discs, and vertebral fractures. Fusion may be effected by the introduction of new bone tissue between the vertebrae to be joined and the stimulation of the natural bone growth capabilities of the vertebrae themselves. In some procedures, spinal discs and/or vertebrae may be replaced with a spacer, or cage, that maintains a proper distance between vertebrae and provides a structure through which the vertebrae may grow and, eventually, fuse together.